To find out how many office workers adjust their chairs, 350 office workers in Spain and the Netherlands are observed and questioned on whether they adjust their chairs. It appears that 24% of 236 Spanish office workers and 61% of 100 Dutch subjects never adjust their chair. If the chair is adjusted, it concerns mostly the seat height. Except for the seat height, other adjustment possibilities are not used by the majority of the study population. Reasons for not adapting could be awareness, complexity of the control system and expected effects.